StarkWare implements quantum-safe locking solution on Bitcoin mainnet, no hard fork required but not yet suitable for large-scale use.

BlockBeats news, October 9 — Starknet published a post introducing the Quantum-Safe Bitcoin (QSB) scheme, stating that StarkWare researchers have verified on the Bitcoin mainnet a quantum-safe locking mechanism that requires no soft fork, no new opcodes, and no changes to consensus rules. The first QSB output was spent on August 26, 2026, in Bitcoin mainnet block 964,199, and the associated GPU computation cost has dropped from an initial approximately $320 to approximately $50.

The scheme was designed by StarkWare researcher Avihu Levy. Its core idea is to use hash computation to build a locking mechanism, avoiding reliance on elliptic curve private keys that could be broken by quantum computers. However, QSB does not mean Bitcoin has achieved comprehensive quantum-resistant security: each transaction requires substantial computation, and moving existing assets into the scheme still requires traditional transactions that carry quantum risk; in addition, QSB transactions do not comply with Bitcoin Core's default relay rules and must be submitted through miners willing to receive transactions directly, and there is currently no accompanying wallet, address format, or recovery process.

StarkWare emphasized that QSB is an emergency research scheme, not a replacement for Bitcoin's quantum-resistant upgrade. The long-term solution still requires introducing post-quantum signature mechanisms through a soft fork. By contrast, Starknet said its underlying STARK proofs have adopted hash-based security mechanisms since their design inception and that it has already formulated a quantum migration roadmap, but as an Ethereum Layer 2, its full realization of quantum-resistant security still depends on the progress of Ethereum's underlying upgrades.

At Token2049, StarkWare CEO Eli Ben-Sasson also raised an open question: whether Starknet should convert to Layer 1 so it can independently advance post-quantum security upgrades without having to fully wait for Ethereum's upgrade timeline. The idea has not yet become a formal decision.